1. Field of the Invention
The present invention relates to an image-reading apparatus, more specifically an image-reading apparatus including a movable image-reading unit.
2. Description of the Related Art
In the related art, in some reading apparatuses, the value of a position counter that indicates a position of an image sensor is stored in a memory such as static-random-access memory (SRAM). When it is determined that the value of the position counter is a normal value, reading of a prepared black-and-white reference board is performed. When the black-and-white reference board has been detected, the image sensor is moved from the position of the black-and-white reference board to a reference position. In addition, U.S. Pat. No. 7,133,165 discloses a method for reading the black-and-white reference board in a case in where it is determined that the value of the position counter is an abnormal value. More specifically, an image sensor is moved in a direction of an origin point, and a temporary reference position is set. Then, reading of the black-and-white reference board is performed while the image sensor is being moved from the temporary reference position. As a result, when the black-and-white reference board has been detected, the image sensor is moved to the original reference position.
However, in the abovementioned reading apparatus, because it is determined only whether the value of the position counter is a normal value or an abnormal value, when the reading apparatus is not properly operated because of a failure other than the counter, it is difficult to set the home position while dealing with the failure. Additionally, because a process of setting the reference position is performed regardless of a power-on state of the reading apparatus, there is a problem, for example, the process of setting the reference position takes a certain time in all cases.
In view of the above-described circumstances, the present invention provides a reading apparatus in which the manner in which the reference position that is used to read an image is set differently depending on the power-on state of the reading apparatus. The reading apparatus can reduce processing time for setting the reference position.